*** There will be spoilers ***
As stated before this is not a very hard task. You could attempt this right from the start, but I advice you to do this on your 2nd run together with Digging up the Past and Good Behaviour (no monster kills) Achievement. On your first run you should do all the sidequests, monster kills and collectibles, because this will be a speedrun that took me a bit more than 3 hours in total. Speedrun -> you will run all the time, so this is a perfect time to kill no monsters, ignore them. Pick the two good choices (Help Cunningham and try to persuade JP) for endings A and C and with the USB trick (explained later) also ending E.
- The first thing you should know, running is your best friend. Fight only if there is absolutely no other way (creep stands inside a door or in a small hallway). But don´t kill them! If you want them to die without ruining "Good behaviour" achievement knock them down on top of some stairs, they will die without raising your kill count ;)
- next point on the list, if you die, you will start again at the last checkpoint with
FULL HEALTH. So don´t waste your medikits if you are near a checkpoint.
- the preorder codes (mentioned under point 2) can be used at 3 places total in the game, but if you insert one of them, all 3 lockers will be filled with this stuff
Walkthrough in short
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1) The start is pretty linear, so not much space here for error. Run to the Devils Pit Stop, inside is a safe (code 26381) containing a Colt. Onward into the Motel and through the Caves toward Hillside.
To start the train you need to press a button combination depending on the difficulty of the Riddles
Easy E | A | C --- Normal A | B | D | C --- Hard D | E | B | A
2) As you exit towards Hillside you will crawl through a hole in the wall inside a room. Here you´ll find the first locker where you can insert one of the following codes:
911977 for Rifle and Golf Club
353479 for Pistol 45 and Baseball Bat
171678 for Nail Gun and Special Axe
Which code you enter depends on what you like most. From the moment you insert one of them all 3 game lockers will be stocked with this items (The other two are hidden in the Basement of the House in Campbell street and at Laymond Ave. Pearl Creek Subway)
Your next destination is the Centennial Building.
Corner of Landsdale Street and Laymond Ave up the ladder with help from the hook, down the stairs and outside. Short chat with Howard and through Logan Park towards the blue marked entry of Centennial Building.
3) The Codes you need to know here are IX -VI - I for the vault door and if you want 851136 for the office of the director (here you get the dias for the vault code so it´s not nessesary to go there). So inside the vault where you enter the roman number code, grab the card of the hanging guy, enjoy the short cut-scene and make your way up to the elevator. Move the wheelchair out of the way, up to floor 18 - cut-scene - escape from Mr. Red Bubble and prepare for the Monastry St. Maria.
4) Inside the Monastry turn left inseide the hallway towards the murder scene behind the Cabinet, pick up the axe. Don´t try to fight the dolls, just turn tail and run away. From here everything is pretty linear, find the 3 verses for or against the Boogeyman
1. Burn the rope and swing the chandelier
2. Theater time, Power up, play the song, light on stage, left switch, right switch, rainmachine and thundehammer and through the forest inside the House
3. X-ray ... you will know what I´m talking about when you are arm deep inside ;)).
Follow the girl, the doors with the Picture of the girl walking into the light are the good ones. Inside the theater, put the chandelier down and the curtain up, light the candles if you want, go backstage.
Left bell 2 times, middle one, right one. Kill the Boogeyman (wait till he strikes, give him one fast swing and back off or shoot him to his knees, you don't need your ammunition any more).
5) Outside the Monastry, go straight towards the Pier (all the way up, follow the street, lower the bridge at Kings Ave. and go left. Here you find the last Part of the "Digging up the Past quest but read on before you dig it up. The locations of the other spots are mentioned in the other guide here
My advice --> make a save on USB or Cloud
before you dig this one out (Sign out, copy your save on USB or Cloud). Then choose from the main menu HDD as save and move on with digging out the last part, this will give you ending E at the end of point 7. After that, continue from your USB/Cloud save and do not dig this one up - this will give you Ending A and C at the end if you followed my advice to not kill any monsters. This way you only have to replay the prison part and not the whole game again.
6) Point of no Return, back to Prison, again really linear, the first code you need is right on your back (11752) and will give you a key for the weapon lockers. Again it´s pretty hard but you can run past all the enemies, so don't waste to much bullets on these guys. Run straight until you get to the cutscene with the fat guy holding the two smaller ones as ... yeah as whatever. Don´t bother fighting him, run immediately left after the cutscene (Workshops letters on the ground) and towards the locked door, insert 22345. Follow your way and fulfill all the tasks till you emerge at a lift where enemies from 3 directions spawn. For this moment you have spared your ammunition. Shoot the 3 waves down, but spare yourself about 10 shots. After that follow the way, run the last time away from the annoying red bubble and arrive at the boss.
7) Left, up, hide behind the "door" until he has finished throwing his furniture at you. Light in the eyes and down to the tubes, pull them out. If he hits you with his punch, take a medi kit immediatly, a second hit will kill you. Repeat the process on the right hand side. Then run left around the boss towards the last two Searchlights and tubes. For this run you have spared your ammo. 3 of this wall guys will roll out and attack you, shoot them out of the way and run. When you make it to the other side, repeat the process of blinding him, then pulling out the tubes.
Congrats, you made it! ;)
What to do with Conningham, read on ...
First run will give you the Surprise Ending (E) for completing "Digging up the past". Your decision on Cunningham doesn´t matter.
Second run will give you Ending A if you spare her and Ending C if you kill her at the end (and if you ignored the monsters and made all good decisions).
I hope this was a bit of help for you, if I forgot something please tell me in the comments! Aaand, sorry for mistakes in grammar and speak, I´m not a native speaker ^^